What is the difference between nuclear batteries and nuclear power plants?

Mars opportunity rover, there are a lot of lace news, the reason is that NASA released the news, said today it encountered sandstorms, do not get enough sunlight to power shortage, sabotage; Over time and it is gaining more and more sunshine, however, because of too much dust on the solar panels will need to remove, sabotage...

Look, this is the limitation of using solar energy, space exploration, then, if the use of nuclear energy?

One of the most successful model

The thought of outer space energy access, many people first thought is outer space atmosphere shade, sun fierce power. However, if we carefully analyze, in space exploration, nuclear power is far more than the solar!

From the Angle of looking at the sun each planet size contrast

Above, the planets in the solar system from the point of view of the size, can be seen, on Mars is better, how much from the sun than the earth seem small, but if you want to explore Saturn, Uranus, Neptune, and the dwarf planet Pluto, using solar energy is not to say that cant, but the difficulty is too big, almost no feasibility.

How to do? Does human space exploration can only be limited to the mercury, Venus, and Mars? Obviously, this is not possible, and at this point, the use of nuclear energy is no longer an alternative, it is an alternative.

And so the actual situation:

Explore Saturn cassini - huygens use of the nuclear batteries

Explore Pluto \"new horizons\" also USES the nuclear batteries

In addition to the above detector, the use of nuclear battery detector and voyager 1, voyager 2, Ulysses, and curious - and so on.

Voyager 1 launched on September 5, 1977, has been flying more than 38 years. In 2015, voyager 1, more than 19.9 billion kilometers from earth, this is equivalent to the earth from the sun 133 times. If you are looking at the sun from the voyager 1, you will find that the brightness of the sun with a normal star makes no difference. At this point, voyager 1 is surrounded by a dark space, without access to solar energy, so, if we put our hopes on the sun, will make our space exploration can only be limited to a small scope in the solar system.

According to NASA, voyager 1 has left the solar system, the signal while traveling at the speed of light, but to the earth from the voyager 1 also need to be 18 and a half hours, even so, it is also in constant sent information on the edge of the solar system for the human, this state will last until 2025, nuclear battery until it is no longer work.

From 1977 to 2025, this period for 48 years, nearly half a century, such a long time, in addition to the nuclear battery, what is the battery can replace it? There are currently no.

The difference between the nuclear battery and nuclear power plant

Nuclear power, nuclear batteries also power, whats the difference between the two?

A difference:

Nuclear reactor, it is the chief of the fission reaction, that is, under a neutron bombardment of uranium 235 split into two medium-sized nuclei, and sent out two or three neutrons.

And nuclear battery mainly use plutonium - 238, through the decay of plutonium - 238, released alpha particles and generate heat. This heat is used to generate electricity.

The graph is plutonium - 238

The graph is plutonium - 238

Plutonium is the element number 94, it is natural, the quality of the heaviest elements in nature is more heavier than uranium. The stable isotope is plutonium - 244, the half-life is about eighty million.

And plutonium - 238 has a half-life of 87.74 years, alpha particles released when decay, release large amounts of heat at the same time, it has very few, even if its plutonium - 238 under certain conditions can also be spontaneous combustion.

Plutonium to spontaneous combustion, which makes it look like a glowing embers.

1 kg of plutonium - 238 thermal power is equivalent to a 570 watts of electric furnace, and duration in decades, never stopped.

Curiosity on the use of nuclear battery and use plutonium - 238, at the beginning of the task can be in any situation steadily providing about 125 watts of power output, and 14 years later also can keep around 100 watts of power.

Difference between 2:

Nuclear fission in the hot, is through the coolant circulation took heat, then the second loop coolant heat water, produce the impact of high temperature steam turbine and generator. Nuclear battery is to use thermoelectric effect to generate electricity.

Lets demonstrate thermoelectric effects:

In the above two cups, with cold water, placed on the left to the right of the add hot water for a while.

The hot water in the right of the cup

The fans began to turn it

Have a free electron in metal, and with the energy of a free electron and the different speed, what factors can decide the electronic energy and speed? Fever is one of important factors, when the ends of the metal conductor temperature difference asynchrony, electronic spread more easily from the hot end to the end of the cold, form the voltage, this is called the thermoelectric effect.

Thermoelectric effect diagram

, cassini - huygens nuclear battery, on the launch in October 1997, cassini - huygens, with 3 pieces of nuclear battery, the nuclear fuel battery for plutonium - 238, it was made into plutonium oxide ceramic piece, can provide 880 watts of power in 1997, ten years later, in 2010, cassini - huygens \"on nuclear battery can also provide 670 watts of power.

From the Apollo 12, astronaut Alan bean out of nuclear battery picture.

In fact, from the Apollo 12, has been to try to use the Apollo 17 nuclear battery, models for the SNAP - 27

The heat up to 1480 watts, transformation of electric power is 73 watts.

Nuclear battery thermoelectric conversion rate is not high, however, nuclear battery are also not only can be used to power generation, especially on the moon, night for half a month, its temperature can reach two hundred degrees Celsius below zero. Nuclear battery to provide the heat energy can make the spacecraft on some sensitive parts to withstand the test of low temperature.

In addition, the recently released film \"Mars rescue\", the inside of the actor is also dug up on Mars before buried nuclear battery heating on Mars, it was able to drive away.

Left for the opportunity rover first, the second like a toy car, it is a pathfinder, intermediate engineers, most the right side is curiosity, curiosity did not use solar panels, rely on nuclear batteries, you look it that size.

Nuclear battery let curiosity have plenty of energy, enabled it to laser melted rock for research.

The graph is curiosity on nuclear batteries

Nuclear power for the first time applied to space in 1961, with more than half a century to now, today, the human is more and more use of nuclear energy in the exploration of space. In the future, if human want to make more progress on space exploration, or if you want to out of the solar system, navigate and explore the fascinating universe outside, then the nuclear technology and nuclear power is a choice.

Maybe it is a fact, communities depend leave the mountain, near the sea eat sea from the sea.

Cant get away from dependence on the sun, how can you bathed in light from another star?